a. Field of the invention. This invention relates to rockets.
b. Prior art. Two stage rockets are known. The stages are arranged in series, with the second stage being stacked atop the first stage. The first stage is ignited and propels the rocket until its fuel is exhausted, at which time the two stages are separated and the fuel in the second stage is ignited to continue propulsion of the second stage.
One of the disadvantages of a typical two stage rocket is that the second stage of the rocket is very unstable during staging, i.e., the period between burnout of the first stage and full operation of the second stage, especially if the two stages separate in the atmosphere rather than above it. The reason for this is that, for a short time, the second stage has no aerodynamic control surfaces or thrust vector control to overcome destabilizing aerodynamic moments.
Another disadvantage of conventional two stage rockets is that, frequently, the first stage is not completely burned out when ignition begins in the second stage. This prevents a clean separation of the two stages and the first stage, still under propulsion, may re-contact the second stage and interfere with the trajectory of the second stage.